The present invention relates to equipment structures or enclosures that are placed in proximity to humans or animals which can be a noise nuisance due to the emanating sounds of fans or buzzing transformers etc., that are mounted inside. The fans can turn on and off based on heat loading and this sound level change disturbs humans as well as causes dogs to bark due to their extended frequency range of hearing. This can greatly compound the noise nuisance issue. Heretofore this has been a necessary evil because of societal demands for electricity or cell phone service provided by the equipment enclosure or structure that is the source of the noise.
A sound wave is the mechanical movement of energy through a medium. The sound energy causes the medium to oscillate which transfers the energy through the medium, molecule to adjacent molecule. These mechanical waves can only be produced in media which possess elasticity and inertia. Sound waves are similar to the ripples on the surface of water when disturbed by a rock.
The energy entering a mechanical system, such as electricity, powers a fan motor, which spins the fan blades or armature, stimulates the surrounding equipment structure or enclosure through transmitted sound energy or vibration that travels through a medium, such as the air in the exhaust vent path, or the metal that the equipment structure or enclosure is made. This transmitted sound energy transfers to the equipment structure or enclosure as well and can modulate the external air surrounding it and cumulatively transmit audible sound away from the equipment structure or enclosure that can be heard by humans or animals.
Prior approaches to solving this problem have attempted to manipulate sound with a variety of electronic circuits, such as the “Acoustic Abatement Method and Apparatus” described in U.S. Pat. No. 3,936,606 by Ronald L. Wanke. U.S. Pat. No. 2,043,416 by Paul Luer titled “Process of Silencing Sound Oscillations” transforms acoustic oscillations into electrical signals, and then reproduces them on another apparatus suitably spaced from a microphone to reproduce the sound at a different phase which cancels the original sound. None of these electrically active methods diminish the original sound levels as simply and passively as the present method and system described herein.